1. Field of the Invention
The present invention relates to a multicomponent polyurethane/vinyl ester hybrid foam system for forming a gradient foam with soft and rigid foam regions, as well as to its use as a material for coating surfaces and for filling openings, cable and pipe bushings in walls, floors and/or ceilings of buildings with foam for the purpose of sound insulation and/or fire protection.
2. Description of the Prior Art
Multicomponent polyurethane foam systems for filling openings, cable and pipe bushings in walls, floors and/or ceilings of buildings with foam for the purpose of fire protection are known. The essential task of the polymer matrix of such a foam system is to function as a binder for the actual fire-retardant additives, such as intumescing materials based on an acid-forming agent, a compound supplying carbon and a gas-forming agent or also on expanding graphite, expandable phyllosilicates and/or additional organic or inorganic flame retardants.
Aside from the actual fire protection requirements, such foam systems for fire protection must constantly meet additional requirements, such as an improvement in sound insulation, etc. These requirements must be taken into account essentially by the properties of the polymer binder.
The conventional polyurethane foam systems for filling openings, cable and pipe bushings in walls, floors and/or ceilings of buildings with foam for the purpose of fire protection usually provide a rigid foam. On the other hand, fire protection plugs of soft polyurethane foam are also known for the same purpose; however, they are not foamed on site and instead are fitted into the openings after having been foamed. Rigid foams, based on polyurethane, are advantageous because of their structural advantages, particularly their higher mechanical load-carrying capability. On the other hand, they are less advantageous for sound insulation, since, because of their hardness, they are less suitable for reducing the transfer of sound through solids. On the other hand, soft polyurethane foams have advantages in sound insulation due to their better dampening of the transfer of sound through solids; however, in their mechanical properties, they are inferior to rigid foams. The suppression of shrinkage of the foam during the development of a foamed product can be achieved more easily with rigid foams than with soft foams. Therefore, polyurethane foam systems, which combine the advantages of a soft foam with those of a rigid foam, would be ideal for fire protection as well as for sound insulation.
U.S. Pat. No. 5,091,436 A discloses hybrid rigid foams of polyurethane and unsaturated polyesters, which are used as a wood substitute. Such rigid hybrid foams are produced using polyisocyanates, polyols, catalysts, water as blowing agent and a hydroxyvinyl ester by foaming in a mold. However, because of their rigid foam structure, these rigid hybrid foams are unsatisfactory as sound insulation materials.
Accordingly, it is an object of the present invention to make a polyurethane foam system available for passive fire protection, which has the advantageous mechanical and fire-protection properties of rigid polyurethane foam systems and, at the same time, the better sound insulation properties of soft polyurethane foam systems.